, the focus returns to remembering the victims. ceremonies in new york, virginia and pennsylvania pay tribute to the 2,752 victims killed when terrorists hijacked four commercial planes and attacked the u.s. in lower manhattan, 9/11 families gather at zuccotti park, adjacent toground zero. throughout the morning, as has become tradition, victims of moments l be read and of silence will be marked when each plane hit and each tower fell. at the pentagon, president obama delivers remarks and participates in a wreath-laying ceremony at the memorial site. and in shanksville, pennsylvania, where united flight 93 crashed, first lady michelle obama, along with former first lady, laura bush, attend a ceremony to honor the passengers who foughback. meanwhile, plans to rebuild at ground zero are moving forward. the centerpiece, one world trade center, is expected to be completed by 2013. but with each construction step forward,here remains a connection to the past. steel beams pulled from the ground zero rubble were permanently installed this week at the entrance of the national september 11th memorial